One of the oldest and most storied traditions of the Senate made a sudden return to Capitol Hill on Wednesday when a junior senator seized control of the chamber with an hours-long ­filibuster involving rambling speeches aimed at blocking a vote on President Obama’s choice to lead the CIA.

Led by Sen. Rand Paul (R-Ky.) with help from other junior senators, the filibuster stretched nearly 13 hours — with the Senate adjourning at about 12:40 a.m. Thursday — and was aimed at drawing attention to deep concern on both sides of the aisle about the administration’s use of unmanned aerial drones in its fight against terrorists and whether the government would ever use them in the United States.

Shortly before noon, Paul — the scion of a political family at the heart of the libertarian movement — came to the Senate floor and declared his opposition to the nomination of John O. Brennan, Obama’s choice to lead the spy agency, who has overseen the drone program.

“I will speak until I can no longer speak,” Paul said as he began. “I will speak as long as it takes, until the alarm is sounded from coast to coast that our Constitution is important, that your rights to trial by jury are precious, that no American should be killed by a drone on American soil without first being charged with a crime, without first being found to be guilty by a court.”

The filibuster is legend and endlessly controversial in the Senate, but extended ones are relatively rare, especially in the modern-day Senate, where the chamber’s rules are used more often to block legislation or to hold show votes on trivial matters. The modern filibuster usually deprives the majority of the 60 votes needed to end debate on a measure or a nomination. Brennan probably has the 60 votes to end a filibuster, which is why Paul’s filibuster required him to actually talk.

Paul’s talking filibuster was the first conducted by a senator since December 2010, when Sen. Bernard Sanders (I-Vt.) held the Senate floor for more than eight hours to oppose a tax-cut plan Obama proposed.

The record for the longest filibuster belongs to Sen. Strom Thurmond (R-S.C.), who spoke for 24 hours and 18 minutes beginning on Aug. 28, 1957, in opposition to civil rights legislation. During his remarks, Thurmond recited from the Declaration of Independence, the Bill of Rights, George Washington’s farewell address and other historical documents.

As Paul spoke, a collection of security guards, Senate pages and tourists kept watch. During one stretch, a man responsible for operating the Senate television cameras was seen reading a newspaper.

Paul said he was “alarmed” by a lack of definition for who can be targeted by drone strikes. He suggested that many colleges in the 1960s were full of people who may have been considered enemies of the state.

“Are you going to drop . . . a Hellfire missile on Jane Fonda?” he asked at one point.

Repeatedly, Paul suggested that his cause was not partisan and not meant as a personal attack on the president — only on his drone policy. Concern about the administration’s use of drones has been part of the debate on the left and the right, and that was reflected in some responses to Paul’s filibuster.

Adding bipartisan credibility to the effort, Sen. Ron Wyden (D-Ore.) — the most outspoken liberal antagonist of the CIA — praised Paul for pushing Brennan to clarify whether the CIA could ever target Americans on U.S. soil.

“When I asked the president, ‘Can you kill an American on American soil?’ it should have been an easy answer. It’s an easy question. It should have been a resounding, an unequivocal, ‘No,’ ” Paul said. “The president’s response? He hasn’t killed anyone yet. We’re supposed to be comforted by that.”

“I would be here if it were a Republican president doing this,” Paul added. “Really, the great irony of this is that President Obama’s opinion on this is an extension of George Bush’s opinion.”

About 3 p.m., several other junior Republicans joined Paul from their seats in the far right corner of the chamber. By tradition, the most junior senators of either party occupy the far corners of the room, with the more tenured members sitting closer to the middle.

Under the rules, the senator from Kentucky was allowed to yield to another senator “for a question,” but no rules mandate the form or length of the question. So Sens. Ted Cruz (Tex.) and Mike Lee (Utah) delivered long speeches in opposition to the drone program, sometimes stopping to ask Paul a question, other times going on for extended periods.

During his remarks, Cruz compared Paul to another famous — if fictional — senator.

“You’re standing here like a modern-day ‘Mr. Smith Goes to Washington,’ ” he said. “You must surely be making Jimmy Stewart smile.”

Paul, Cruz and Lee spoke out against the CIA nominee from contiguous desks in the deep right corner of the room. Later, they were joined briefly by Republican Sens. John Barasso (Wyo.), Saxby Chambliss (Ga.), John Cornyn (Tex.), Mitch McConnell (Ky.), Jerry Moran (Kan.), Marco Rubio (Fla.), John Thune (S.D.), and Patrick J. Toomey (Pa.), all of whom voiced support.

Senate Democrats said they received no warning of Paul’s intent to filibuster for most of Wednesday. Majority Leader Harry M. Reid (D-Nev.) had hoped to move Brennan’s nomination to a final vote Wednesday, but aides said it would be moved to Thursday.

Brennan’s nomination easily cleared the Senate Intelligence Committee this week, suggesting that he would have the 60 votes required to end Paul’s filibuster and bring the nomination to a vote. He has gained the support of some Republican senators, even as others want to hold up his nomination in hopes of getting more answers from the White House about the deaths of four Americans in an attack on a U.S. diplomatic outpost in Benghazi, Libya, on Sept. 11.

Throughout the day, Paul conceded that Brennan would ultimately get the job.

“I don’t know how long I’ll be able to do this, so I can’t ultimately stop the nomination,” he said late in the afternoon. “But what I can do is try to draw attention to this and try to get an answer.”